Process of and apparatus for regulating synchronous motors controlling the speed of converter collector-brushes.



C. G. K PPITZ. PROCESSOF AND APPARATUS FOR REGULATIHG SYNCHRONOUS MOTORS CONTROLLING THE SPEED OF CONVERTER COLLECTOR BRUSHES.

APPLICATION FILED OCT. I0, 1912- Patented May 23, 1916.

UNITED STATES PATENT OFFICE.

CARL e. izorrirz, or YOUNGSTOWN, OHIO.

PROCESS OF AND APPARATUS FOR REGULATIN G SYNCHRONOUS MOTORS CONTROLLING THE SPEED OF CONVERTER COLLECTOR-BRUSHES.

Specification of Letters Patent.

Patented May 23, 1916.

Application filed October 10, 1912. Serial No. 724,965.

verter Collector-Brushes, of which the following is a specification.

In my application Ser. No. 646,988, filed -August '31, 1911, I have described and claimed an apparatus for interconverting polyphase and direct electric currents having a potential of from one or two to several hundred thousand volts, in which polyphase currents traverse a closed winding and unidirectional currents are transferred as arcs between segments connected to, successive portions of said windings and brushes revolving in synchronism with the polyphase current. In said application, a direct-current motor controlled or kept in step by a synchronous motor energized by the polyphase current, was illustrated for driving the brushes. Provision was made for shifting the angular position of the brushes simply to change the ratio of-the voltages of the impressed and converted currents. According to the present invention the speed of such a synchronous control-motor is regulated and a fixed frequency maintained by changing the phase relation between the E. M. F. impressed on the primary winding of the converter and the counter E. M. F. of the synchronous motor. This may be accomplished by several methods, but a preferred method of maintaining the fixed frequency is by changing the phase relation of voltages impressed on the synchronous motor to the axis of current transfer.

Figure 1 illustrates a group of three alternating-current voltage-waves, successively lagging in position; and Fig. 2 is a diagrammatic View of a converter with a brush-driving shaft the speed of which is controlled by a synchronous motor, provided with means for regulating the speed of this motor and the brushes.

In Fig. 1, the curve A is the E. M. F. induced in winding 2, of Fig. 2, .while curves B and 0 show the counter E. M. F. of the synchronous motor in two different positions with respect to this induced E. M. F. In the operation of this converter three E. M. F.s are concerned, namely,that im-* pressed on primary winding 1, due to the rotation of the brushes; second, the secondary -E. M. F. induced in the secondary windmg 2, of Fig. 2, which may without materlal error be assumed to be in opposition (or in phase) with that in 1, and which is the E. M. F. impressed on the terminals of the synchronous motor, and third, the counter E. M. Fxof the synchronous motor.

It is desired to maintain a fixed frequency on the A. C. side when converting from D. G. and to do so by changing the phase relation between the E. M. F.s represented by curves A and B. In operation, the counter E. M. F. B lags sufliciently behind, A to allow the synchronous motor to take suflicient current to maintain its normal speed, and therefore, normal frequency, in overcoming frictional and other loss of the rotating parts, but these losses never remain constant which necessitates an automatic regulating feature. If these losses increase, the phase relation of the above E. M. F.s may be so shifted as to bring the counter E. M. F. B of the synchronous motor to position C causing the motor to take more power. Conversely, if these losses should decrease, the lag is changed to some position less than that shown at B and the motor takes less power. According to the present invention the angle of lag, or phase relation between A and B is continuously varied to maintain the desired speed and frequency, either by shifting the ring of collector-segments of motor frame, or, as shown, for example, in my copending ap plication No. 646,988, above noted, by interposing an angle shifting device on the shaft between the motor and the brushes, ihereby shifting the points of current trans- Fig. 2 illustrates a converter of the type shown in my specified application, comprisnism with the current in said windings, means for controlling the relative s eed of said segments and brushes, comprising a synchronous motor in circuit with said winding, and devices for shifting the angle of current-transfexi" between said segments and brushes relative to the phase winding.

In testimony whereof I aflix my. signature in presence oftwo witnesses.

CARL G. KOPPITZ. Witnesses:

J. W. BLACKBURN, B. M. GEE.

copies of this patient may be obtained for live cents each, by addrening the Commissioner of r atents,

Washington, D. 0." 

